1 // Copyright 2008 Christophe Henry 2 // henry UNDERSCORE christophe AT hotmail DOT com 3 // This is an extended version of the state machine available in the boost::mpl library 4 // Distributed under the same license as the original. 5 // Copyright for the original version: 6 // Copyright 2005 David Abrahams and Aleksey Gurtovoy. Distributed 7 // under the Boost Software License, Version 1.0. (See accompanying 8 // file LICENSE_1_0.txt or copy at 9 // http://www.boost.org/LICENSE_1_0.txt) 10 11 #ifndef BOOST_MSM_BACK_DISPATCH_TABLE_H 12 #define BOOST_MSM_BACK_DISPATCH_TABLE_H 13 14 #include <utility> 15 16 #include <boost/mpl/reverse_fold.hpp> 17 #include <boost/mpl/greater.hpp> 18 #include <boost/mpl/filter_view.hpp> 19 #include <boost/mpl/pop_front.hpp> 20 #include <boost/mpl/for_each.hpp> 21 #include <boost/mpl/advance.hpp> 22 23 #include <boost/type_traits/is_base_of.hpp> 24 #include <boost/type_traits/is_same.hpp> 25 26 #include <boost/msm/event_traits.hpp> 27 #include <boost/msm/back/metafunctions.hpp> 28 #include <boost/msm/back/common_types.hpp> 29 30 BOOST_MPL_HAS_XXX_TRAIT_DEF(is_frow) 31 32 namespace boost { namespace msm { namespace back 33 { 34 35 // Generates a singleton runtime lookup table that maps current state 36 // to a function that makes the SM take its transition on the given 37 // Event type. 38 template <class Fsm,class Stt, class Event,class CompilePolicy> 39 struct dispatch_table 40 { 41 private: 42 // This is a table of these function pointers. 43 typedef HandledEnum (*cell)(Fsm&, int,int,Event const&); 44 typedef bool (*guard)(Fsm&, Event const&); 45 46 // class used to build a chain (or sequence) of transitions for a given event and start state 47 // (like an UML diamond). Allows transition conflicts. 48 template< typename Seq,typename AnEvent,typename State > 49 struct chain_row 50 { 51 typedef State current_state_type; 52 typedef AnEvent transition_event; 53 54 // helper for building a disable/enable_if-controlled execute function 55 struct execute_helper 56 { 57 template <class Sequence> 58 static 59 HandledEnum executeboost::msm::back::dispatch_table::chain_row::execute_helper60 execute(Fsm& , int, int, Event const& , ::boost::mpl::true_ const & ) 61 { 62 // if at least one guard rejected, this will be ignored, otherwise will generate an error 63 return HANDLED_FALSE; 64 } 65 66 template <class Sequence> 67 static 68 HandledEnum executeboost::msm::back::dispatch_table::chain_row::execute_helper69 execute(Fsm& fsm, int region_index , int state, Event const& evt, 70 ::boost::mpl::false_ const & ) 71 { 72 // try the first guard 73 typedef typename ::boost::mpl::front<Sequence>::type first_row; 74 HandledEnum res = first_row::execute(fsm,region_index,state,evt); 75 if (HANDLED_TRUE!=res && HANDLED_DEFERRED!=res) 76 { 77 // if the first rejected, move on to the next one 78 HandledEnum sub_res = 79 execute<typename ::boost::mpl::pop_front<Sequence>::type>(fsm,region_index,state,evt, 80 ::boost::mpl::bool_< 81 ::boost::mpl::empty<typename ::boost::mpl::pop_front<Sequence>::type>::type::value>()); 82 // if at least one guards rejects, the event will not generate a call to no_transition 83 if ((HANDLED_FALSE==sub_res) && (HANDLED_GUARD_REJECT==res) ) 84 return HANDLED_GUARD_REJECT; 85 else 86 return sub_res; 87 } 88 return res; 89 } 90 }; 91 // Take the transition action and return the next state. executeboost::msm::back::dispatch_table::chain_row92 static HandledEnum execute(Fsm& fsm, int region_index, int state, Event const& evt) 93 { 94 // forward to helper 95 return execute_helper::template execute<Seq>(fsm,region_index,state,evt, 96 ::boost::mpl::bool_< ::boost::mpl::empty<Seq>::type::value>()); 97 } 98 }; 99 // nullary metafunction whose only job is to prevent early evaluation of _1 100 template< typename Entry > 101 struct make_chain_row_from_map_entry 102 { 103 // if we have more than one frow with the same state as source, remove the ones extra 104 // note: we know the frow's are located at the beginning so we remove at the beginning (number of frows - 1) elements 105 enum {number_frows = ::boost::mpl::count_if< typename Entry::second,has_is_frow< ::boost::mpl::placeholders::_1> >::value}; 106 107 //erases the first NumberToDelete rows 108 template<class Sequence, int NumberToDelete> 109 struct erase_first_rows 110 { 111 typedef typename ::boost::mpl::erase< 112 typename Entry::second, 113 typename ::boost::mpl::begin<Sequence>::type, 114 typename ::boost::mpl::advance< 115 typename ::boost::mpl::begin<Sequence>::type, 116 ::boost::mpl::int_<NumberToDelete> >::type 117 >::type type; 118 }; 119 // if we have more than 1 frow with this event (not allowed), delete the spare 120 typedef typename ::boost::mpl::eval_if< 121 typename ::boost::mpl::bool_< number_frows >= 2 >::type, 122 erase_first_rows<typename Entry::second,number_frows-1>, 123 ::boost::mpl::identity<typename Entry::second> 124 >::type filtered_stt; 125 126 typedef chain_row<filtered_stt,Event, 127 typename Entry::first > type; 128 }; 129 // helper for lazy evaluation in eval_if of change_frow_event 130 template <class Transition,class NewEvent> 131 struct replace_event 132 { 133 typedef typename Transition::template replace_event<NewEvent>::type type; 134 }; 135 // changes the event type for a frow to the event we are dispatching 136 // this helps ensure that an event does not get processed more than once because of frows and base events. 137 template <class FrowTransition> 138 struct change_frow_event 139 { 140 typedef typename ::boost::mpl::eval_if< 141 typename has_is_frow<FrowTransition>::type, 142 replace_event<FrowTransition,Event>, 143 boost::mpl::identity<FrowTransition> 144 >::type type; 145 }; 146 // Compute the maximum state value in the sm so we know how big 147 // to make the table 148 typedef typename generate_state_set<Stt>::type state_list; 149 BOOST_STATIC_CONSTANT(int, max_state = ( ::boost::mpl::size<state_list>::value)); 150 151 template <class Transition> 152 struct convert_event_and_forward 153 { executeboost::msm::back::dispatch_table::convert_event_and_forward154 static HandledEnum execute(Fsm& fsm, int region_index, int state, Event const& evt) 155 { 156 typename Transition::transition_event forwarded(evt); 157 return Transition::execute(fsm,region_index,state,forwarded); 158 } 159 }; 160 161 // A function object for use with mpl::for_each that stuffs 162 // transitions into cells. 163 struct init_cell 164 { init_cellboost::msm::back::dispatch_table::init_cell165 init_cell(dispatch_table* self_) 166 : self(self_) 167 {} 168 // version for transition event not base of our event 169 // first for all transitions, then for internal ones of a fsm 170 template <class Transition> 171 typename ::boost::disable_if< 172 typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type 173 ,void>::type init_event_base_caseboost::msm::back::dispatch_table::init_cell174 init_event_base_case(Transition const&, ::boost::mpl::true_ const &, ::boost::mpl::false_ const &) const 175 { 176 typedef typename create_stt<Fsm>::type stt; 177 BOOST_STATIC_CONSTANT(int, state_id = 178 (get_state_id<stt,typename Transition::current_state_type>::value)); 179 self->entries[state_id+1] = reinterpret_cast<cell>(&Transition::execute); 180 } 181 template <class Transition> 182 typename ::boost::enable_if< 183 typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type 184 ,void>::type init_event_base_caseboost::msm::back::dispatch_table::init_cell185 init_event_base_case(Transition const&, ::boost::mpl::true_ const &, ::boost::mpl::false_ const &) const 186 { 187 self->entries[0] = reinterpret_cast<cell>(&Transition::execute); 188 } 189 190 // version for transition event is boost::any 191 // first for all transitions, then for internal ones of a fsm 192 template <class Transition> 193 typename ::boost::disable_if< 194 typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type 195 ,void>::type init_event_base_caseboost::msm::back::dispatch_table::init_cell196 init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::true_ const &) const 197 { 198 typedef typename create_stt<Fsm>::type stt; 199 BOOST_STATIC_CONSTANT(int, state_id = 200 (get_state_id<stt,typename Transition::current_state_type>::value)); 201 self->entries[state_id+1] = &convert_event_and_forward<Transition>::execute; 202 } 203 template <class Transition> 204 typename ::boost::enable_if< 205 typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type 206 ,void>::type init_event_base_caseboost::msm::back::dispatch_table::init_cell207 init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::true_ const &) const 208 { 209 self->entries[0] = &convert_event_and_forward<Transition>::execute; 210 } 211 212 // version for transition event base of our event 213 // first for all transitions, then for internal ones of a fsm 214 template <class Transition> 215 typename ::boost::disable_if< 216 typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type 217 ,void>::type init_event_base_caseboost::msm::back::dispatch_table::init_cell218 init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::false_ const &) const 219 { 220 typedef typename create_stt<Fsm>::type stt; 221 BOOST_STATIC_CONSTANT(int, state_id = 222 (get_state_id<stt,typename Transition::current_state_type>::value)); 223 self->entries[state_id+1] = &Transition::execute; 224 } 225 template <class Transition> 226 typename ::boost::enable_if< 227 typename ::boost::is_same<typename Transition::current_state_type,Fsm>::type 228 ,void>::type init_event_base_caseboost::msm::back::dispatch_table::init_cell229 init_event_base_case(Transition const&, ::boost::mpl::false_ const &, ::boost::mpl::false_ const &) const 230 { 231 self->entries[0] = &Transition::execute; 232 } 233 // Cell initializer function object, used with mpl::for_each 234 template <class Transition> 235 typename ::boost::enable_if<typename has_not_real_row_tag<Transition>::type,void >::type operator ()boost::msm::back::dispatch_table::init_cell236 operator()(Transition const&,boost::msm::back::dummy<0> = 0) const 237 { 238 // version for not real rows. No problem because irrelevant for process_event 239 } 240 template <class Transition> 241 typename ::boost::disable_if<typename has_not_real_row_tag<Transition>::type,void >::type operator ()boost::msm::back::dispatch_table::init_cell242 operator()(Transition const& tr,boost::msm::back::dummy<1> = 0) const 243 { 244 //only if the transition event is a base of our event is the reinterpret_case safe 245 init_event_base_case(tr, 246 ::boost::mpl::bool_< 247 ::boost::is_base_of<typename Transition::transition_event,Event>::type::value>(), 248 ::boost::mpl::bool_< 249 ::boost::msm::is_kleene_event<typename Transition::transition_event>::type::value>()); 250 } 251 252 dispatch_table* self; 253 }; 254 255 // Cell default-initializer function object, used with mpl::for_each 256 // initializes with call_no_transition, defer_transition or default_eventless_transition 257 // variant for non-anonymous transitions 258 template <class EventType,class Enable=void> 259 struct default_init_cell 260 { default_init_cellboost::msm::back::dispatch_table::default_init_cell261 default_init_cell(dispatch_table* self_,cell* tofill_entries_) 262 : self(self_),tofill_entries(tofill_entries_) 263 {} 264 template <class State> 265 typename ::boost::enable_if<typename has_state_delayed_event<State,Event>::type,void>::type operator ()boost::msm::back::dispatch_table::default_init_cell266 operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<0> = 0) 267 { 268 typedef typename create_stt<Fsm>::type stt; 269 BOOST_STATIC_CONSTANT(int, state_id = (get_state_id<stt,State>::value)); 270 cell call_no_transition = &Fsm::defer_transition; 271 tofill_entries[state_id+1] = call_no_transition; 272 } 273 template <class State> 274 typename ::boost::disable_if< 275 typename ::boost::mpl::or_< 276 typename has_state_delayed_event<State,Event>::type, 277 typename ::boost::is_same<State,Fsm>::type 278 >::type 279 ,void >::type operator ()boost::msm::back::dispatch_table::default_init_cell280 operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<1> = 0) 281 { 282 typedef typename create_stt<Fsm>::type stt; 283 BOOST_STATIC_CONSTANT(int, state_id = (get_state_id<stt,State>::value)); 284 cell call_no_transition = &Fsm::call_no_transition; 285 tofill_entries[state_id+1] = call_no_transition; 286 } 287 // case for internal transitions of this fsm 288 template <class State> 289 typename ::boost::enable_if< 290 typename ::boost::mpl::and_< 291 typename ::boost::mpl::not_<typename has_state_delayed_event<State,Event>::type>::type, 292 typename ::boost::is_same<State,Fsm>::type 293 >::type 294 ,void>::type operator ()boost::msm::back::dispatch_table::default_init_cell295 operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<2> = 0) 296 { 297 cell call_no_transition = &Fsm::call_no_transition_internal; 298 tofill_entries[0] = call_no_transition; 299 } 300 dispatch_table* self; 301 cell* tofill_entries; 302 }; 303 304 // variant for anonymous transitions 305 template <class EventType> 306 struct default_init_cell<EventType, 307 typename ::boost::enable_if< 308 typename is_completion_event<EventType>::type>::type> 309 { default_init_cellboost::msm::back::dispatch_table::default_init_cell310 default_init_cell(dispatch_table* self_,cell* tofill_entries_) 311 : self(self_),tofill_entries(tofill_entries_) 312 {} 313 314 // this event is a compound one (not a real one, just one for use in event-less transitions) 315 // Note this event cannot be used as deferred! 316 // case for internal transitions of this fsm 317 template <class State> 318 typename ::boost::disable_if< 319 typename ::boost::is_same<State,Fsm>::type 320 ,void>::type operator ()boost::msm::back::dispatch_table::default_init_cell321 operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<0> = 0) 322 { 323 typedef typename create_stt<Fsm>::type stt; 324 BOOST_STATIC_CONSTANT(int, state_id = (get_state_id<stt,State>::value)); 325 cell call_no_transition = &Fsm::default_eventless_transition; 326 tofill_entries[state_id+1] = call_no_transition; 327 } 328 329 template <class State> 330 typename ::boost::enable_if< 331 typename ::boost::is_same<State,Fsm>::type 332 ,void>::type operator ()boost::msm::back::dispatch_table::default_init_cell333 operator()(boost::msm::wrap<State> const&,boost::msm::back::dummy<1> = 0) 334 { 335 cell call_no_transition = &Fsm::default_eventless_transition; 336 tofill_entries[0] = call_no_transition; 337 } 338 dispatch_table* self; 339 cell* tofill_entries; 340 }; 341 342 public: 343 // initialize the dispatch table for a given Event and Fsm dispatch_tableboost::msm::back::dispatch_table344 dispatch_table() 345 { 346 // Initialize cells for no transition 347 ::boost::mpl::for_each<typename generate_state_set<Stt>::type, 348 boost::msm::wrap< ::boost::mpl::placeholders::_1> > 349 (default_init_cell<Event>(this,entries)); 350 351 // build chaining rows for rows coming from the same state and the current event 352 // first we build a map of sequence for every source 353 // in reverse order so that the frow's are handled first (UML priority) 354 typedef typename ::boost::mpl::reverse_fold< 355 // filter on event 356 ::boost::mpl::filter_view 357 <Stt, boost::mpl::or_< 358 ::boost::is_base_of<transition_event< ::boost::mpl::placeholders::_>, Event>, 359 ::boost::msm::is_kleene_event<transition_event< ::boost::mpl::placeholders::_> > 360 > 361 >, 362 // build a map 363 ::boost::mpl::map<>, 364 ::boost::mpl::if_< 365 // if we already have a row on this source state 366 ::boost::mpl::has_key< ::boost::mpl::placeholders::_1, 367 transition_source_type< ::boost::mpl::placeholders::_2> >, 368 // insert a new element in the value type 369 ::boost::mpl::insert< 370 ::boost::mpl::placeholders::_1, 371 ::boost::mpl::pair<transition_source_type< ::boost::mpl::placeholders::_2>, 372 ::boost::mpl::push_back< 373 ::boost::mpl::at< ::boost::mpl::placeholders::_1, 374 transition_source_type< ::boost::mpl::placeholders::_2> >, 375 change_frow_event< ::boost::mpl::placeholders::_2 > > 376 > >, 377 // first row on this source state, make a vector with 1 element 378 ::boost::mpl::insert< 379 ::boost::mpl::placeholders::_1, 380 ::boost::mpl::pair<transition_source_type< ::boost::mpl::placeholders::_2>, 381 make_vector< change_frow_event< ::boost::mpl::placeholders::_2> > > > 382 > 383 >::type map_of_row_seq; 384 // and then build chaining rows for all source states having more than 1 row 385 typedef typename ::boost::mpl::fold< 386 map_of_row_seq,::boost::mpl::vector0<>, 387 ::boost::mpl::if_< 388 ::boost::mpl::greater< ::boost::mpl::size< 389 ::boost::mpl::second< ::boost::mpl::placeholders::_2> >, 390 ::boost::mpl::int_<1> >, 391 // we need row chaining 392 ::boost::mpl::push_back< ::boost::mpl::placeholders::_1, 393 make_chain_row_from_map_entry< ::boost::mpl::placeholders::_2> >, 394 // just one row, no chaining, we rebuild the row like it was before 395 ::boost::mpl::push_back< ::boost::mpl::placeholders::_1, 396 get_first_element_pair_second< ::boost::mpl::placeholders::_2> > 397 > >::type chained_rows; 398 // Go back and fill in cells for matching transitions. 399 ::boost::mpl::for_each<chained_rows>(init_cell(this)); 400 } 401 402 // The singleton instance. 403 static const dispatch_table instance; 404 405 public: // data members 406 // +1 => 0 is reserved for this fsm (internal transitions) 407 cell entries[max_state+1]; 408 }; 409 410 }}} // boost::msm::back 411 412 413 #endif //BOOST_MSM_BACK_DISPATCH_TABLE_H 414 415